Eli5: how come our body heat increases during exercise?

Question

While working out our body sweats to cool us down but shouldn’t the blood in our body also? With our blood flowing even faster during this period shouldn’t it be cooled by the sweat/air around us and cool our muscles from within?

In: 1

Answer 1

The body is roughly 20-25% efficient at converting food energy to muscle motion, so when we exercise there is a lot of extra heat to get rid of.